Last week I focused on the Ketzos’ understanding of hefker as a form of neder which allows others access to one’s property without actually surrendering ownership. This understanding was implied by the Rambam’s statement:
ההפקר אף על פי שאינו נדר הרי הוא כמו נדר שאסור לו לחזור בו
R’ Shimon Shkop (Sha'arei Yosher 5:23) strongly disagrees with the Ketzos’s approach. R’ Shimon’s simplest argument stems from terminology – if hefker is just another flavor of neder, then why introduce a new term to describe it? But R’ Shimon’s disagreement is about more than semantics. The Mishna in Shvi’is presents a debate between Beis Shamai and Beis Hillel whether one can be mafkir property only to the poor to the exclusion of the rich. The Yerushalmi provides derashos as the basis of both positions. If hefker is just another form of neder, why would one not be able to be mafkir something only to the poor or only to the rich just as one can make a neder excluding a particular person from having hana’ah from an item? Why would the Yerushalmi need derashos when we already have a parsha of nedarim?
Some other interesting proofs R’ Shimon offers: a non-Jew can declare property hefker, but is not obligated to fulfill nedarim. It is possible to be sho’el on a neder and retroactively undo it, but it is not possible to be sho’el on hefker (see Ran Nedarim 85a).
Interestingly, the GR”A makes a girsa change in the Rambam that also suggests hefker in not exactly the same as neder. The Rambam as we have it says “asur lachzor bo”, it is prohibited to retract hefker, ostensibly meaning the same prohibition of bal yacheil which prohibits not fulfilling a neder applies here. The GR”A’s text of the Rambam reads “aino yachol lachzor bo”, one is unable to retract hefker, meaning that unlike nedarim, there is no issur of retracting, but nonetheless it may not be done.